This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Although oxidative stress is known to be involved early in the etiologies of both normal aging and neurodegenerative disease, lack of a noninvasive assay for brain oxidative status has limited development of antioxidant based interventions. The hypotheses of this proposal is that magnetic resonance spectroscopy (MRS) can provide a noninvasive assay for human brain antioxidant concentrations that can be used to: identify influences responsible for compromised antioxidant levels, diagnose reduced antioxidant capacity prior to appearance of symptoms or structural damage, and monitor antioxidant capacity throughout therapeutic intervention. In part 1 of this study, a novel noninvasive MRS assay will be used to quantify levels of the two most concetnrated non-enzymatic antioxidants in the central nervous system, reduced glutathione (GSH) and vitamin C (Asc) in two homogenous human populations, a young and an elder cohort. In the second part, this antioxidant profile will be measured under the respective endogenous and exogenous influences of aging and diet. The role of the GCRC will be to assist in the implementation of appropriate dietary control for this study. The key role of the GCRC in this study will be to assess deitary habits and to provide a vitamin C controlled diet for three days prior to each MR exam. The GCRC will also evaluate fruit and vegetable screeners so that only cadidates who consume fewer than five fruits and vegetables per day are enrolled. This inclusion criteria was selected in order to optimize feasibility of measuring a difference in pre- versus post- vitamin C supplementation. The GCRC will also council participants regarding the need to refrain from intentional and incidental vitamin C supplementation. In order to potentially correlate brain and serum Asc levels, the nursing staff from the GCRC will collect blood for measurement of serum vitamin C concentrations complimentary to each MR scan. The GCRC will also label (attached), store, dispense, and keep an accountability log (attached) for vitamin C supplements which will be provided to elder participants.